What Makes Flamingos So Stable While Standing on One Leg?

Scientists have long wondered why flamingos stand on one leg when they rest. Biologists Young-Hui Chang of the Georgia Institute of Technology and Lena Ting of Emory University don’t know why yet, but they think they know how. Instead of using muscles to balance on one leg, flamingos have a unique skeletal system that locks when the flamingo centers its body weight over the leg. All the joints, essentially, snap into place, in balance. The scientists noted very little wavering, and suggested that flamingos sleep on one leg because it requires less energy. In other words, they’re more stable on one leg than two.

A unique leg to stand on:

Flamingos have two main joints in their legs. The one you can see, which bends backward, is the ankle. A flamingo’s knee -- the stabilizing joint -- is hidden by feathers at the base of the bird’s body.

“If you look at the bird from the front, while they’re standing on one leg, the foot is directly beneath the body, which means their leg is angled inward. That’s the pose you have to strike in order to engage the stay mechanism,” Chang explains.

The researchers also studied a bird cadaver, and found that the passive locking leg mechanism was still operable, prompting the conclusion that this passive mechanism does not require active muscle force.